MySQL双主复制，即互为Master-Slave(只有一个Master提供写操作)，可以实现数据库服务器的热备，但是一个Master宕机后不能实现动态切换。而Keepalived通过虚拟IP，实现了双主对外的统一接口以及自动检查、失败切换机制。联合使用，可以实现MySQL数据库的高可用方案。


环境描述：
OS：CentOS6.5_X64
MASTER：192.168.196.133
BACKUP：192.168.196.134
VIP：192.168.196.135

操作系统时间一致更改：

# date -s "20170707 01:51:42"
# hwclock --systohc

1按照之前的文章,搭建双主备机


2安装keepalived

[root@backup ~]# yum install -y pcre-devel openssl-devel popt-devel #安装依赖包
[root@master ~]# wget http://www.keepalived.org/software/keepalived-1.2.7.tar.gz 
[root@master ~]# tar zxvf keepalived-1.2.7.tar.gz 
[root@master ~]# cd keepalived-1.2.7 
[root@master ~]#./configure --prefix=/usr/local/keepalived 
[root@master ~]#make && make install

3将keepalived配置成系统服务

[root@master ~]# cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/ 
[root@master ~]# cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/ 
[root@master ~]# mkdir /etc/keepalived/ 
[root@master ~]# cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/ 
[root@master ~]# cp /usr/local/keepalived/sbin/keepalived /usr/sbin/

4修改配置文件

[root@master ~]# vi /etc/keepalived/keepalived.conf 
! Configuration File for keepalived

global_defs {
   notification_email {
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id MYSQL_HA       #标识，双主相同 
}

vrrp_instance VI_1 {
    state BACKUP            #两台都设置BACKUP 
    interface eth1
    virtual_router_id 51    #主备相同 
    priority 100            #优先级，backup设置90 
    advert_int 1
    nopreempt                 #不主动抢占资源，只在master这台优先级高的设置，backup不设置 
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.196.135
    }
}

virtual_server 192.168.196.135 3306 {
    delay_loop 2
    #lb_algo rr        #LVS算法，用不到，我们就关闭了 
    #lb_kind NAT        #LVS模式，如果不关闭，备用服务器不能通过VIP连接主MySQL 
    nat_mask 255.255.255.0
    persistence_timeout 50
    protocol TCP

    real_server 192.168.196.133 3306 {      #检测本地mysql，backup也要写检测本地mysql 
        weight 3
        notify_down /usr/local/keepalived/mysql.sh    #当mysq服down时，执行此脚本，杀死keepalived实现切换 
        TCP_CHECK { 
                connect_timeout 3    #连接超时 
                nb_get_retry 3      #重试次数 
                delay_before_retry 3 #重试间隔时间 
        } 
    }
}
}[root@master ~]# vi /usr/local/keepalived/mysql.sh 
    #!/bin/bash
    pkill keepalived
[root@master ~]# chmod +x /usr/local/keepalived/mysql.sh 
[root@master ~]# /etc/init.d/keepalived start


#backup服务器只修改priority为90、nopreempt不设置、real_server设置本地IP。


5授权两台Mysql服务器允许root远程登录，用于在其他服务器登陆测试！

mysql>grant all privileges on *.* to 'root'@'%' identified by 'root';

mysql>flush privileges


6、测试高可用性

    1、通过Mysql客户端通过VIP连接，看是否连接成功。

    2、停止master这台mysql服务，是否能正常切换过去，可通过ip addr命令来查看VIP在哪台服务器上。


mysql 配置双热 keepalived+mysql双主热备_服务器

    3、可通过查看/var/log/messges日志，看出主备切换过程
    4、master服务器故障恢复后，是否主动抢占资源，成为活动服务器。